Power amplifier module

Abstract

A power amplifier module includes first and second amplifiers, a first bias circuit, and an adjusting circuit. The first amplifier amplifies a first signal. The second amplifier amplifies a second signal based on an output signal from the first amplifier. The first bias circuit supplies a bias current to the first amplifier via a current path on the basis of a bias drive signal. The adjusting circuit includes an adjusting transistor having first, second, and third terminals. A first voltage based on a power supply voltage is supplied to the first terminal. A second voltage based on the bias drive signal is supplied to the second terminal. The third terminal is connected to the current path. The adjusting circuit adjusts the bias current on the basis of the power supply voltage supplied to the first amplifier.

What is claimed is: 
     
       1. A power amplifier module comprising:
 a first amplifier supplied with a power supply voltage and configured to amplify a first signal; 
 a second amplifier configured to amplify a second signal based on an output signal from the first amplifier; 
 a first bias circuit configured to supply a bias current to the first amplifier based on a bias drive signal, the bias current being supplied via a current path; and 
 an adjusting circuit comprising:
 an adjusting transistor having first, second, and third terminals, wherein a first voltage based on the power supply voltage is supplied to the first terminal, a second voltage based on the bias drive signal is supplied to the second terminal, and the third terminal is connected to the current path. 
 
 
     
     
       2. The power amplifier module according to  claim 1 , wherein:
 the adjusting circuit further comprises first, second, and third resistor elements, 
 the first voltage is supplied from a power supply terminal to the first terminal of the adjusting transistor via the first resistor element, 
 the second voltage is supplied to the second terminal of the adjusting transistor via the second resistor element, and 
 the third terminal of the adjusting transistor is connected to the current path via the third resistor element. 
 
     
     
       3. The power amplifier module according to  claim 1 , wherein:
 the power amplifier module is configured to operate in a first operation mode or a second operation mode, a power level of an output signal of the power amplifier module being greater in the second operation mode than in the first operation mode, 
 the first amplifier comprises:
 at least one first unit transistor that is ON when the power amplifier module operates in the first operation mode or the second operation mode; and 
 at least one second unit transistor that is OFF when the power amplifier module operates in the first operation mode and that is ON when the power amplifier module operates in the second operation mode, and 
 
 the first bias circuit is configured to supply the bias current to the at least one first unit transistor of the first amplifier. 
 
     
     
       4. The power amplifier module according to  claim 2 , wherein:
 the power amplifier module is configured to operate in a first operation mode or a second operation mode, a power level of an output signal of the power amplifier module being greater in the second operation mode than in the first operation mode, 
 the first amplifier comprises:
 at least one first unit transistor that is ON when the power amplifier module operates in the first operation mode or the second operation mode; and 
 at least one second unit transistor that is OFF when the power amplifier module operates in the first operation mode and that is ON when the power amplifier module operates in the second operation mode, and 
 
 the first bias circuit is configured to supply the bias current to the at least one first unit transistor of the first amplifier. 
 
     
     
       5. The power amplifier module according to  claim 3 , wherein:
 the second amplifier comprises:
 at least one third unit transistor that is ON when the power amplifier module operates in the first operation mode or the second operation mode; and 
 at least one fourth unit transistor that is OFF when the power amplifier module operates in the first operation mode and that is ON when the power amplifier module operates in the second operation mode, 
 
 the power amplifier module further comprises:
 a second bias circuit configured to supply a second bias current to the at least one first unit transistor and the at least one second unit transistor; 
 a third bias circuit configured to supply a third bias current to the at least one third unit transistor; 
 a fourth bias circuit configured to supply a fourth bias current to the at least one third unit transistor; and 
 a fifth bias circuit configured to supply a fifth bias current to the at least one fourth unit transistor, 
 
 when the power amplifier module operates in the first operation mode, the first and third bias circuits are driven to supply the bias current and third bias current, respectively, and 
 when the power amplifier module operates in the second operation mode, the second, fourth, and fifth bias circuits are driven to supply the second, fourth, and fifth bias currents, respectively. 
 
     
     
       6. The power amplifier module according to  claim 4 , wherein:
 the second amplifier comprises:
 at least one third unit transistor that is ON when the power amplifier module operates in the first operation mode or the second operation mode; and 
 at least one fourth unit transistor that is OFF when the power amplifier module operates in the first operation mode and that is ON when the power amplifier module operates in the second operation mode, 
 
 the power amplifier module further comprises:
 a second bias circuit configured to supply a second bias current to the at least one first unit transistor and the at least one second unit transistor; 
 a third bias circuit configured to supply a third bias current to the at least one third unit transistor; 
 a fourth bias circuit configured to supply a fourth bias current to the at least one third unit transistor; and 
 a fifth bias circuit configured to supply a fifth bias current to the at least one fourth unit transistor, 
 
 when the power amplifier module operates in the first operation mode, the first and third bias circuits are driven to supply the bias current and the third bias current, respectively, and 
 when the power amplifier module operates in the second operation mode, the second, fourth, and fifth bias circuits are driven to supply the second, fourth, and fifth bias currents, respectively.